Boxplot: Presidential Terms
This box plot (also known as box and whiskers) is laid out for the term of each President in chronological order from President H.W.Bush through President Donald Trump. The far right shows the Dow Jones Index from January 3, 2001 through September 27, 2019.
The dark green boxes display the 50th percentile of data with the light green line representing the mean.
The whiskers indicate the 75th percentile on the top and the 25th percentile on the bottom.
The black circles are the outliers.
Because the means, the box sizes, and the whiskers are relatvely the same across all these President's terms and also with the Dow Jones index for the (almost) 20 year history, the conclusion is that the President doesn't measureably affect the stock market.